The operation of a liquid-cooled electric drive, which comprises at least one electric machine and a pulse inverter with associated power electronics, requires electric coolant pumps which are supplied via the 12V on-board power supply. The additional pumps serve to ensure a minimum volume flow in the components so that the waste heat is transferred to the cooling medium due to the resulting power loss of the components. The cooling medium is then cooled in the cooling unit and returned to the components. In an electric vehicle with a multi-machine concept, both the front axle and the rear axle are connected to the cooling system.
If cooling problems occur that lead to a reduced coolant volume flow or a failure of the coolant volume flow, the resulting waste heat leads to the failure of all electric drives in the vehicle, within a very short time. The vehicle can no longer be moved independently.
In most cases, modern electric vehicles are equipped with several electric drives.
For example, DE 199 03 443 A1 describes a drive unit for an electrically powered vehicle. The vehicle uses a gearbox in which at least two electric machines are accommodated in a gearbox housing and operated alternately.
Special designs of liquid-cooled e-machines are already known in which the coolant is distributed in the e-machine without an additional coolant pump.
DE 10 2004 049 795 A1, for example, discloses a cooling device for an electric machine that can be cooled with a cooling liquid, in which cooling liquid is introduced into a rotor of an electric machine via a feed device and is distributed within the electric machine by the acting centrifugal forces. The cooling liquid is discharged from the electric machine via a discharge device and fed to a cooling liquid cooler.
DE 29 42 811 A1 discloses a liquid cooling device for the rotor winding of an electric machine. The electric machine circulates a cooling liquid using centrifugal pressure.
Against this background, the object of the present invention is to least partially eliminate the disadvantages of the prior art.